https://www.gamespot.com/articles/destiny-2-how-to-get-a-powerful-weapon-from-factio/1100-6453641/

Destiny 2's Faction Rallies event is going on now. Part of this is a contest of sorts where the Faction that collects the most packages by October 3 can buy a "powerful weapon." You can see the Faction-specific rewards in the tweet below. They all look pretty great.

Dead Orbit has a scout rifle, FWC a pulse rifle, and New Monarchy a sidearm. If you're in the winning faction, you'll be able to buy your faction's "powerful weapon" for 1,000 glimmer. If not, you can purchase your faction's weapon for 50,000 glimmer. What we don't know, however, is the Power Level of the weapons, though that should become clear soon.